The grass contact is only part of the picture
IFAB Law 9 requires the whole ball to pass beyond the boundary line, whether on the ground or in the air. Seeing daylight between the ball’s contact patch and the paint is therefore not enough by itself.
Imagine looking straight down at a ball resting beside a touchline. Its lowest point is outside the line, but its curved side still projects above the paint. A low camera may show the outside contact point clearly while hiding that overhang. The ball’s three-dimensional shape explains the apparent disagreement.
Compare views with the same question
A camera looking along the line is useful for a different reason from one looking across it. The first can help judge whether any part overlaps the line’s vertical plane; the second often tells you more about who touched it. Neither angle becomes conclusive merely because it is a close-up.
Pause before the player’s next touch and trace the entire outline, including the upper curve. If the view is obstructed, say that the angle does not show the full ball rather than treating an uncertain image as proof of an error. This method also helps explain a ball that briefly travels outside the field in the air: its position above the line counts just as its position on the turf does.
Questions answered
Is the painted line itself outside?
The whole ball must pass beyond it for the boundary test.
Can the ball be out without touching the ground outside?
Yes; the same test applies in the air.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.